This links you to a portion of the teensreadtoo website. In addition to providing book reviews (although they are not necessarily by professionals), this site has other information such as the YALSA Quick Picks for Reluctant Young Adult Readers list. This gets you the list of books and then you may take that list to look for reviews.
Why is this good? After the book description if the book has reviews from reputable review sources such as Booklist, School Library Journal and so on, they are all there in one spot.
Young Adult Library Services Association. (2010). 2010 Quick Picks for Reluctant Young Adult Readers.
http://teensreadtoo.com/2010QuickPicks.htmlhttp://www.ala.org/ala/mgrps/divs/yalsa/yalsa.cfm
Title Wave (Follett Library Resources)
School Library Journal
www.amazon.com